A typical rolling cone earth-boring bits has a bit body that rotatably supports three cones. Each of the cones has a gage surface, a central area and a nose area. The central area contains at least two rows of cutting elements. The nose area also contains one or more cutting elements. The cutting elements may be integrally formed with the cone metal or they may be hard metal inserts installed within mating holes formed in the cone. Bits utilizing inserts typically have gage inserts fitted within mating holes on the gage surface.
Both the cutting elements in the central area and the nose area may have a variety of shapes. Common shapes for inserts used in these areas include hemispherical, ovoid and chisel-shaped. The central area cutting elements typically disintegrate rock by crushing action. The outermost row of central area cutting elements, called the heel row, disintegrate rock by both a crushing and shearing mode. The nose cutting elements also disintegrate by both a crushing and shearing mode.
The gage inserts typically engage the sidewall of the borehole in shearing action. These inserts have flat tops or outer ends, typically bounded by conical bevels. The flat outer ends are located in a plane parallel with the gage surface, when viewed in cross-section.